Bortezomib may stabilize pediatric renal transplant recipients with antibody-mediated rejection.

BACKGROUND: Current therapeutic strategies to effectively treat antibody-mediated rejection (AMR) are insufficient. Thus, we aimed to determine the benefit of a therapeutic protocol using bortezomib for refractory C4d + AMR in pediatric kidney transplant patients.

METHODS: We examined seven patients with treatment-refractory C4d + AMR. Immunosuppression included antithymocyte globulin or anti-CD25 monoclonal antibody for induction therapy with maintenance corticosteroids, calcineurin inhibitor, and anti-metabolite. Estimated glomerular filtration rate (eGFR) calculated by the Schwartz equation, biopsy findings assessed by 2013 Banff criteria, and human leukocyte antigen (HLA) donor-specific antibodies (DSA) performed using the Luminex single antigen bead assay were monitored pre- and post- bortezomib therapy.

RESULTS: Seven patients (86 % male, 86 % with ≥6/8 HLA mismatch, and 14 % with pre-formed DSA) age 5 to 19 (median 15) years developed refractory C4d + AMR between 1 and 145 (median 65) months post-transplantation. All patients tolerated bortezomib. One patient had allograft loss. Of the six patients with surviving grafts (86 %), mean pre-bortezomib eGFR was 42 ml/min/1.73 m(2) and the mean 1 year post-bortezomib eGFR was 53 ml/min/1.73 m(2). Five of seven (71 %) had improvement of histological findings of AMR, C4d staining, and/or acute cellular rejection. Reduction in HLA DSAs was more effective for class I than class II.

CONCLUSIONS: Bortezomib appears safe and may correlate with stabilization of eGFR in pediatric kidney transplant patients with refractory C4d + AMR.